Nano imprinting with reusable polymer template with metallic or oxide coating

ABSTRACT

Methods and systems are provided for fabricating polymer-based imprint lithography templates having thin metallic or oxide coated patterning surfaces. Such templates show enhanced fluid spreading and filling (even in absence of purging gases), good release properties, and longevity of use. Methods and systems for fabricating oxide coated versions, in particular, can be performed under atmospheric pressure conditions, allowing for lower cost processing and enhanced throughput.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/922,953 filed Oct. 26, 2015, which is a continuation of U.S. patentapplication Ser. No. 14/216,017 filed Mar. 17, 2014, now U.S. Pat. No.9,170,485, which claims the benefit under 35 U.S.C. §119(e)(1) of U.S.Provisional No. 61/792,280 filed on Mar. 15, 2013; all of which areincorporated by reference herein.

BACKGROUND INFORMATION

Nano-fabrication includes the fabrication of very small structures thathave features on the order of 100 nanometers or smaller. One applicationin which nano-fabrication has had a sizeable impact is in the processingof integrated circuits. The semiconductor processing industry continuesto strive for larger production yields while increasing the circuits perunit area formed on a substrate; therefore nano-fabrication becomesincreasingly important. Nano-fabrication provides greater processcontrol while allowing continued reduction of the minimum featuredimensions of the structures formed. Other areas of development in whichnano-fabrication has been employed include biotechnology, opticaltechnology, mechanical systems, and the like.

An exemplary nano-fabrication technique in use today is commonlyreferred to as imprint lithography. Exemplary nanoimprint lithographyprocesses are described in detail in numerous publications, such as U.S.Pat. No. 8,349,241, U.S. Pat. No. 8,066,930, and U.S. Pat. No.6,936,194, all of which are hereby incorporated by reference herein.

A nanoimprint lithography technique disclosed in each of theaforementioned U.S. patents includes formation of a relief pattern in aformable (polymerizable) layer and transferring a pattern correspondingto the relief pattern into an underlying substrate. The substrate may becoupled to a motion stage to obtain a desired positioning to facilitatethe patterning process. The patterning process uses a template spacedapart from the substrate and a formable liquid applied between thetemplate and the substrate. The formable liquid is solidified to form arigid layer that has a pattern conforming to a shape of the surface ofthe template that contacts the formable liquid. After solidification,the template is separated from the rigid layer such that the templateand the substrate are spaced apart. The substrate and the solidifiedlayer are then subjected to additional processes to transfer a reliefimage into the substrate that corresponds to the pattern in thesolidified layer.

BRIEF DESCRIPTION OF DRAWINGS

So that features and advantages of the present invention can beunderstood in detail, a more particular description of embodiments ofthe invention may be had by reference to the embodiments illustrated inthe appended drawings. It is to be noted, however, that the appendeddrawings only illustrate typical embodiments of the invention, and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

FIG. 1 illustrates a simplified side view of a nanoimprint lithographysystem having a template and a mold spaced apart from a substrate.

FIG. 2 illustrates a simplified view of the substrate illustrated inFIG. 1, having a patterned layer thereon.

FIGS. 3A and 3B illustrate an exemplary method of forming a templateaccording to the invention.

FIGS. 4A and 4B illustrate an exemplary method of imprinting a patternedlayer onto a substrate using the template of FIGS. 3A and 3B.

FIGS. 5A and 5B illustrate another exemplary method of forming atemplate according to the invention.

FIGS. 6A and 6B illustrate yet another exemplary method of forming atemplate according to the invention.

FIG. 7 illustrates a further exemplary method of forming a templateaccording to the invention.

FIG. 8 depicts shear force experimental results of templates accordingto the invention.

FIG. 9 depicts separation force experimental results of a templateaccording to the invention.

FIG. 10 depicts fluid filling experimental results of a templateaccording to the invention.

DETAILED DESCRIPTION

Referring to the figures, and particularly to FIG. 1, illustratedtherein is a nanoimprint lithography system 10 used to form a reliefpattern on substrate 12. Substrate 12 may be coupled to substrate chuck14. As illustrated, substrate chuck 14 is a vacuum chuck. Substratechuck 14, however, may be any chuck including, but not limited to,vacuum, pin-type, groove-type, electrostatic, electromagnetic, and/orthe like. Exemplary chucks are described in U.S. Pat. No. 6,873,087,which is hereby incorporated by reference herein.

Substrate 12 and substrate chuck 14 may be further supported by stage16. Stage 16 may provide translational and/or rotational motion alongthe x, y, and z-axes. Stage 16, substrate 12, and substrate chuck 14 mayalso be positioned on a base (not shown).

Spaced-apart from substrate 12 is template 18. Template 18 may include abody having a first side and a second side with one side having a mesa20 extending therefrom towards substrate 12. Mesa 20 having a patterningsurface 22 thereon. Further, mesa 20 may be referred to as mold 20.Alternatively, template 18 may be formed without mesa 20.

Template 18 and/or mold 20 may be formed from such materials including,but not limited to, fused-silica, quartz, silicon, organic polymers,siloxane polymers, borosilicate glass, fluorocarbon polymers, metal,hardened sapphire, and/or the like. As illustrated, patterning surface22 comprises features defined by a plurality of spaced-apart recesses 24and/or protrusions 26, though embodiments of the present invention arenot limited to such configurations (e.g., planar surface). Patterningsurface 22 may define any original pattern that forms the basis of apattern to be formed on substrate 12.

Template 18 may be coupled to chuck 28. Chuck 28 may be configured as,but not limited to, vacuum, pin-type, groove-type, electrostatic,electromagnetic, and/or other similar chuck types. Exemplary chucks arefurther described in U.S. Pat. No. 6,873,087. Further, chuck 28 may becoupled to imprint head 30 such that chuck 28 and/or imprint head 30 maybe configured to facilitate movement of template 18.

Nanoimprint lithography system 10 may further comprise a fluid dispensesystem 32. Fluid dispense system 32 may be used to deposit formablematerial 34 (e.g., polymerizable material) on substrate 12. Formablematerial 34 may be positioned upon substrate 12 using techniques, suchas, drop dispense, spin-coating, dip coating, chemical vapor deposition(CVD), physical vapor deposition (PVD), thin film deposition, thick filmdeposition, and/or the like. Formable material 34 may be disposed uponsubstrate 12 before and/or after a desired volume is defined betweenmold 22 and substrate 12 depending on design considerations. Formablematerial 34 may be functional nano-particles having use within thebio-domain, solar cell industry, battery industry, and/or otherindustries requiring a functional nano-particle. For example, formablematerial 34 may comprise a monomer mixture as described in U.S. Pat. No.7,157,036 and U.S. Pat. No. 8,076,386, both of which are hereinincorporated by reference. Alternatively, formable material 34 mayinclude, but is not limited to, biomaterials (e.g., PEG), solar cellmaterials (e.g., N-type, P-type materials), and/or the like.

Referring to FIGS. 1 and 2, nanoimprint lithography system 10 mayfurther comprise energy source 38 coupled to direct energy 40 along path42. Imprint head 30 and stage 16 may be configured to position template18 and substrate 12 in superimposition with path 42. System 10 may beregulated by processor 54 in communication with stage 16, imprint head30, fluid dispense system 32, and/or source 38, and may operate on acomputer readable program stored in memory 56.

Either imprint head 30, stage 16, or both vary a distance between mold20 and substrate 12 to define a desired volume therebetween that isfilled by formable material 34. For example, imprint head 30 may apply aforce to template 18 such that mold 20 contacts formable material 34.After the desired volume is filled with formable material 34, source 38produces energy 40, e.g., ultraviolet radiation, causing formablematerial 34 to solidify and/or cross-link conforming to a shape ofsurface 44 of substrate 12 and patterning surface 22, defining patternedlayer 46 on substrate 12. Patterned layer 46 may comprise a residuallayer 48 and a plurality of features shown as protrusions 50 andrecessions 52, with protrusions 50 having a thickness t₁ and residuallayer having a thickness t2.

The above-mentioned system and process may be further employed in nanoimprint lithography processes and systems referred to in U.S. Pat. No.6,932,934, U.S. Pat. No. 7,077,992, U.S. Pat. No. 7,179,396, and U.S.Pat. No. 7,396,475, all of which are hereby incorporated by reference intheir entirety.

Conventional glass, quartz or fused silica templates used in nanoimprintlithography are typically fabricated by e-beam processes, followed bymultiple vacuum processes such as reactive ion etching (RIE). However,such processes are both expensive and time-consuming. Templatereplication processes are known that use lithography (e.g., nanoimprintlithography) to create replica templates in glass (or a similarsubstrate) using an e-beam fabricated master template. While less costlythat direct e-beam fabrication, such glass template replication stillrequires RIE etching to transfer pattern features into the glass,followed by SEM inspection in order to finalize and confirm featuregeometry. These processes are still time-intensive, and can cause abottleneck in high-throughput nanoimprint lithography manufacturingprocesses. Polymer templates, i.e., templates where the patterningsurface of the template is itself formed of a polymeric material (e.g.via lithography processes), can be fabricated more quickly and lessexpensively than glass templates, but they likewise have disadvantages.For example, such polymer templates generally do not have a patterningsurface with high enough surface hardness and strength to achievecomparable durability to glass templates. The polymer template patternfeatures thus are prone to damage through successive imprinting cycles.When in use, polymer templates also typically require continued surfacetreatment for clean pattern separation from the cured, patternedpolymeric material, as such polymer templates generally have highsurface free energy and there is a tendency for polymer-to-polymeradherence which degrades template performance over successive imprintcycles.

Provided herein are polymer templates with a thin metallic or oxidelayer (or layers) on the patterned surface that provides multiplebenefits over current glass or fused silica templates or other polymerbased templates. Also provided are methods of fabricating suchtemplates, and template fabrications systems that incorporate suchmethods.

Referring to FIGS. 3A-3B, template 188 is formed of three layers: basetemplate substrate or layer 12, patterned polymer layer 146 and thinmetal or oxide layer 160 covering patterned layer 146. Base substrate 12can be a Si or glass wafer, glass plate or a flexible film, such as aplastic film. Patterned layer 146 can be formed by UV or thermalimprint, or any other lithography processes. FIGS. 4A-4B depict, inturn, use of template 188 to imprint polymeric material 34 deposited onsubstrate 162 to yield patterned layer 196. The thickness of the metalor oxide layer can be in the range of 2-50 nm. In certain variations,the range can be 2-25 nm, or 2-20 nm, or 2-15 nm, or 2-10 nm.

For metal layers, the types of metal deposited on patterned layer 146 toform layer 160 can be Gold Palladium (AuPd), Silver Palladium (AgPd),Gold (Au), Silver (Ag), Platinum (Pt), or an alloy of any of thesemetals, or multiple layers of any of them. For AuPd and AgPd alloys inparticular, the ratio of Au or Ag to Pd can range from 20:80 to 80:20.Suitable metal deposition methods include e.g. sputtering or evaporationor atomic layer deposition (ALD).

For oxide layers, the types of oxides deposited on patterned layer 146can include e.g. silicon dioxide (SiO₂) or SiO₂-like silicon oxidelayers (SiO_(x)). Suitable oxide deposition methods include e.g.sputtering or chemical vapor deposition (CVD) or ALD. As used hereinchemical vapor deposition (CVD) includes plasma enhanced chemical vapordeposition (PECVD), and atmospheric pressure plasma CVD, includingatmospheric pressure plasma jet (APP-Jet) and atmospheric pressuredielectric barrier discharge (AP-DBD) processes, such as those processesdescribed in “Open Air Deposition of SiO₂ Films by an AtmosphericPressure Line-Shaped Plasma,” Plasma Process. Polym. 2005, 2, 4007-413,and “Plasma-Enhanced Chemical Vapor Deposition of SiO₂ Thin Films atAtmospheric Pressure by Using HMDS/Ar/O₂ , J. Korean Physical Society,Vol. 53, No. 2, 2008, pp. 892896, incorporated herein by reference.

The advantages of the templates provided herein, i.e., templates havinga thin layer of metal(s) or oxide(s) applied on top of a patternedpolymeric layer, are manifold. First, such templates show much betterfluid spreading as compared to glass or polymer templates. Without beingbound by theory, it is believed that liquid imprint resist spreading andtemplate pattern feature filling is enhanced by the hydrophilicproperties of the thin metallic or oxide layer. Such enhanced resistspreading and filling properties are important in enabling high-speedimprinting processes. In particular, in UV imprinting processes usingtemplates of the present invention, observed resist spreading was muchfaster than seen using a fused silica template. Further still, many UVimprint processes at the nanoscale use a helium atmosphere whenimprinting in order to achieve acceptable high-throughput speeds. Ahelium atmosphere minimizes gas trapping that would otherwise occur inambient air, allowing for both faster (and more faithful) featurefilling times than the same process performed in ambient air. That is,helium purging may be necessary for fast and faithful template patternfilling at the nano scale imprinting level. However, helium iscomparably expensive and not always readily available in generalcleanroom facilities. However, given the enhanced resist spreadingdriven by the hydrophilic surface properties of the present inventivetemplates, helium-free UV imprinting is possible even at fine feature(i.e., sub-100 nm) patterning levels.

Second, during template separation the metallic or oxide layercontributes to good release performance by, among other things, blockingthe liquid imprint resist from otherwise adhering to or bonding with theprecured polymer pattern underneath prior to or during curing. Suchpolymer-polymer interactions are a disadvantage of polymer templates forthe reasons previously identified. Also the thin metal or oxide layercan prolong the template useful lifetime by protecting the polymerfeatures underneath. This is proven by pattern longevity test usingsub-100 nm linewidth grating pattern. There is an optimal value in thethickness of metal coating and oxide coating for lowest separation forceand to block the liquid resist from penetrating through it. When thecoating thickness is too thin, separation force will be high since theimprinting layer can intermix with the underlying patterned polymerlayer of the template. As the thickness increases to optimal condition,separation force will drop. As the thickness exceeds the optimalcondition, separation force will be increased since the feature of thetemplate will be stiffened and/or distorted, i.e., the separation forceincreases due to surface stiffening, roughening and pattern interlockingeffect from mushroom-like deposition profile which likewise casespattern profile distortion. Therefore, for a given material and pattern,a separation force test can be used to determine the optimal coatingthickness for the resultant template, as further described herein.

Third, in addition to the enhanced spreading and separation performanceand increased template longevity, the conductive thin metal coating ishelpful in reducing or removing static charges on the template.Reduction or removal of static charges, in turn, reduces the chances ofcharged airborne contaminant particles being attracted to and collectingon the template surface. The presence of such particles on the templatesurface can otherwise cause patterning defects and/or template damage.

Fourth, the fabrication of the polymer template with metallic or oxidecoating provides self linewidth modulation and/or linewidth reductionproperties. For example, if the original polymeric patterns on thetemplate consist of 50/50 nm line/space, an ˜7.5 nm uniform coating ofthe metallic or oxide layer can change the line/space into 65/35 nm.Imprinted features using this type of template will have reverse fillfactor, i.e., 35/65 nm for line/space.

Fifth, fabrication methods provided herein can reduce templatereplication cost and processing time. For example, the fabrication of apolymer template with metallic or oxide coating according to theinvention can be performed in two simple steps; (1) imprinting (to formpattern features) and (2) deposition of the metallic or oxide layercoating material. In particular, for a polymer template with e.g.SiO₂-like (SiO_(x)) coating, an inline atmospheric pressure plasma CVDsystem or other inline atmospheric pressure deposition processes can beutilized. Such processes, which are performed under atmospheric pressureconditions, can significantly lower processing cost and greatly enhancethroughput, as compared to other deposition processes which requirevacuum conditions and higher temperatures. Examples of such processesare depicted in FIGS. 5A-5B.

FIG. 5A shows an atmospheric pressure plasma jet CVD approach fordepositing oxide layer 226 onto previously formed polymer pattern 224 onbase layer 222. Base layer 222 is secured to motion stage 220 andtranslates relative to atmospheric pressure plasma jet (APPJ) system 200which itself is oriented perpendicular to motion stage 220. APPJ system200 consists of first and second plates or bodies 204 and 206 havingfirst and second outer electrodes 212 and 210 disposed thereon,respectively. Inner electrode 208 is disposed between first and secondelectrodes 212 and 210. The electrodes are connected to voltage supply203. Plasma gas (typically O₂/Ar or He mixture) is provided through thetop of the system at input 240. Precursor and carrier gas is providednear the bottom of the inner electrode 212 via supply 202. In operation,plasma/precursor mixture 230 is generated and directed downward towardpatterned layer 224 where it forms oxide layer 226 on patterned layer224 as it is translated relative to system 200.

FIG. 5B shows a similar approach using atmospheric pressure plasmadielectric barrier discharge system (DBD) system 300. Here, first andsecond electrodes 310 and 312 are connected to voltage supply 304 andotherwise disposed in parallel with base layer 322 and patterned polymerlayer 326, with first electrode 310 positioned above patterned polymerlayer 326 and second electrode 312 positioned between motion stage 320and base layer 322. Plasma gas (02/Ar or He mixture) and precursor andcarrier gases are provided through input 340 and supply 302,respectively. In this approach, the template may remain static duringoxide layer 326 formation from generated plasma/precursor mixture 330.

In addition, continuous roll-to-roll methods for translating a flexibleplastic substrate having prepatterned features can also be used forforming templates according to the invention, leading to additional costsavings. Examples of such processes are depicted in FIGS. 6A and 6B,which illustrate the atmospheric pressure plasma jet CVD system andatmospheric pressure plasma dielectric barrier discharge system (DBD) ofFIGS. 5A-5B, respectively, adapted for oxide deposition onto a polymertemplate formed on a flexible film substrate, such as a polycarbonate(PC) film. The flexible substrates can be retained and translatedrelative to the APPJ and APP-DBD systems using e.g. roll-to-roll systemssuch as described in U.S. Patent Publication No. 2013-0214452,incorporated herein by reference in its entirety.

Turning to FIG. 6A, flexible film substrate (or base layer) 422 issupported by rollers 450 and 452 which operate under tension to retainthe substrate in a flat configuration and which, when rotated, cantranslate substrate 422 relative to atmospheric pressure plasma jet(APPJ) system 400. APPJ system 400 is configured as otherwise describedabove with respect to FIG. 5A (i.e., with voltage source 403 connectedto outer electrodes 410 and 412 positioned on opposing plates 406 and404 and with inner electrode 408 disposed in between, together withplasma gas input 440 and precursor and carrier gas supply 402, andoperating such that generated plasma/precursor mixture 430 is directeddownward and deposited onto patterned polymer layer 424, thereby formingoxide layer 426). With reference to FIG. 6B, rollers 550 and 552likewise support and retain flexible film substrate (or base layer) 522and operates as described above with respect to the roller system ofFIG. 6A such that substrate 522 is translated relative to APP-DBD system500. APP-DBD system 500 is configured as otherwise described above withrespect to FIG. 5B (i.e., with voltage source 504 connected to opposingparallel electrodes 510 and 512 with electrode 510 positioned abovepatterned polymer layer 524 and electrode 512 positioned below substrate522, together with plasma gas input 540 and precursor and carrier gassupply 502, and operating such that generated plasma/precursor mixture530 deposits onto patterned polymer layer 524, thereby forming oxidelayer 526).

Further still, such atmospheric pressure processes as described withrespect to FIGS. 6A and 6B can be combined with imprint lithographypatterning techniques (also done at atmospheric pressure) such thatpatterning of the precursor substrate (e.g., glass or plastic film) canbe directly followed by oxide coating of the patterned layer, therebyproviding for continuous, in-line processes for fabricating suchtemplates. An example of such a process is depicted in FIG. 7 whichdepicts imprinting of a flexible substrate with to form a polymerictemplate immediately followed by metal or oxide layer deposition viaatmospheric pressure plasma jet (APPJ) system similar to that of FIG.6A. More particularly, system 600 includes rollers 650 and 652 undertension with additional support rollers 654, 656, 658, and 660 whichcollectively operate to support and retain flexible film substrate 622in a flat configuration and translate the substrate across a series ofpositions. In the imprinting step, substrate 622 is translated from afirst position to a second position during which fluid dispense system32 deposits droplets of polymerizable material 34 onto substrate 622while master template 612 (connected to a template chuck on a motionstage not shown) is moved into superimposition with and co-translateswith substrate 622 such that polymerizable material fills the reliefpattern of master template 612. Energy source 606 provides actinicenergy to cure polymerizable material 34 and form patterned polymerlayer 624 during such co-translation. Master template 612 is thenseparated from formed layer 624 and returned to its initial position.Substrate 622 is then fed from the second position to a third position.Roller belt system 640, comprising rollers 642 and 644, is provided tomaintain tension on substrate 622 during such movement, with belt system646 further having protective film 646 that protects features ofpatterned polymer layer 624 from damage as it translates around roller642. Substrate 622 containing patterned polymer layer 624 is thentranslated from the third to fourth position and in the process passesbeneath APPJ system 670 which essentially operates as system 400described above with respect to FIG. 6A to deposit oxide layer 626 ontopatterned polymer layer 624 (i.e., voltage source 603 is connected toouter electrodes 610 and 611 positioned on opposing plates 605 and 604and with inner electrode 608 disposed in between, together with plasmagas input 642 and precursor and carrier gas supply 602, and operatingsuch that generated plasma/precursor mixture 630 is directed downwardand deposited onto patterned polymer layer 624, thereby forming oxidelayer 626 on patterned polymer layer 624 as substrate 622 is translatedpast APPJ system 670).

EXAMPLES Metal-Coated Polymer Templates Example 1: Metal Layer ThicknessDetermination

Shear force testing was used to determine optimal coating thicknessesfor various AuPd coating thicknesses. Silicon wafer substrates werecoated with an adhesion layer, with a UV curable imprint resist fluid(MonoMat™, Molecular Imprints, Austin, Tex.) in turned deposited viasmall droplets onto the adhesion layer and then imprinted with a blankimprint template and cured to form a flat polymeric layer. AuPd(60%/40%) was sputtered onto the polymeric layer using an Edwards S150BSputter Coater (Edwards Ltd., West Sussex, UK) at various sputteringtimes ranging from 0-180 seconds, resulting in corresponding AuPd layerthicknesses as follows: 0 sec (0 nm); 10 sec (2 nm); 30 sec (5 nm); 60sec (9 nm); 90 sec (12 nm); 120 sec (18 nm); 180 sec (26 nm). Shearforce tests were performed with each AuPd coated sample using an InstronModel 5524 force tester (Instron, Norwood, Mass.). The same UV curableimprint resist was deposited onto each AuPd coated sample, then placedin contact with the test specimen of the force tester (which itself wastreated the same adhesion layer as above), followed by curing of theimprint resist. Each sample was then subjected to shear force testingwith the results shown in the graph of FIG. 8. Glass test specimens(with and without an adhesion layer) were also tested as controls. Asobserved, shear force decreased at longer sputtering times up to a 90second sputter time, which corresponds to a 10-15 nm AuPd layer. Thissample had the lowest shear force (at 3.00 lbf), and corresponds to thelowest anticipated separation force in use. However, longer sputteringtimes beyond 90 seconds caused an increase shear (and thus separationforce), likely due to increased sputtering time resulting in surfaceroughening of the AuPd layer, which can increase total surface contactarea with the cured resist, thereby increasing in turn the adhesionforce that must be overcome.

Example 2: Template Formation

Metal coated polymer templates with 130 nm pitch gratings (65 nm linewidth; 65 nm space width) were prepared as follows. A silicon mastertemplate having 130 nm pitch gratings as above was loaded onto aroll-to-roll imprinting tool (LithoFlex™ 100, Molecular Imprints,Austin, Tex.) and then the pattern was transferred to 170 um thickpolycarbonate film by drop deposition of the UV curable imprint resistfluid as in Example 1 above onto the polycarbonate film followed byimprinting with the silicon master template to form patterned polymericlayers on the polycarbonate film having same dimensions (i.e., 130 nmpitch gratings with 65 nm line width and 65 nm space width). Thesepatterned polymer layers were then subjected to AuPd or AgPd sputteringas described in Example 1 above, each for approximately 90 secondssputtering (12 nm target thickness) to form AuPd or AgPd coated polymertemplates at the following ratios: AuPd (75:25), AgPd (60:40) and AgPdat 30:70.

Example 3: Patterning Performance

The templates of Example 2 were subjected to imprint testing as follows.Imprint resist fluid as above was drop-dispensed onto adhesion layertreated silicon wafers and imprinted using the AuPd and AgPd polymertemplates of Example 2. Imprinting was performed by hand rolling underatmospheric pressure conditions. Once cured, template separation wasalso done by a manual peel-off method. The resultant imprinted patternedlayers on the silicon wafers were evaluated for visible defects,including global or local separation failure and/or feature shearing,breaking or distortion. Each template exhibited good pattern transferwithout showing any local or global separation failure, or featureshearing, breakage or distortion.

Example 4: Separation Force

An AuPd (60%/40%) coated polymer template was prepared as in Example 2above but with a 60 nm half-pitch (60 nm line width, 60 nm space width)concentric gratings pattern. The template was sputtered forapproximately 90 seconds to form an approximately 12 nm layer. Thistemplate was subjected to multiple imprint testing, as described inExample 3, and the separation force observed was compared to theseparation force observed when using a standard fused silica template ofthe same pattern dimensions. The results are depicted in FIG. 9 (withdata from the standard fused silica template identified by referenceletter “A”; and data from the AuPd polymer template identified byreference letter “B”). Both templates exhibited a lowering of separationforce over successive imprints (from initial separation force at about20 N down to levels of 10N or less after the 5^(th) successive imprint),with the sample template similar in overall separation performance ascompared to the fused silica template.

Example 5: Fluid Filling

The template of Example 4 above was subjected to machine imprint testingusing HD700 imprint lithography tool (Molecular Imprints, Austin, Tex.)Fluid spread and fill times were monitored during imprinting. For eachtemplate, images were obtained of fluid spreading and filling at 3seconds, 5 seconds, and 10 seconds, and these images were comparedagainst those obtained using the standard fused silica template of thesame pattern dimensions under identical conditions. These images aredepicted at FIG. 10, with column “A” images corresponding to the fusedsilica template and the column “B” images corresponding to the Example 3template. As can be observed, the Example 3 template provides enhancedfluid spreading and filling as compared to the fused silica template.The Example 3 template showed complete spreading and filling within 5seconds, whereas the fused silica template still had not completelyspread and filled by 10 seconds.

Example 6: Template Longevity

The template of Example 3 was subjected to 100 x continuous imprinttesting according to the procedures described in Example 3. After the100th imprint there was still no imprint pattern degradation or anyindication of global or local separation failure.

Oxide Coated Polymer Templates Example 7: Template Formation (VacuumDeposition) and Patterning Performance

Oxide-coated polymer templates were prepared as otherwise describedabove in Example 2 but with silicon dioxide (SiO₂) substituted for AuPdor AgPd and deposited by PECVD. A PTI-790 deposition system(Plasma-Therm, St. Petersburg, Fla.) was used to deposit SiO₂ in variousthicknesses onto the pre-patterned film to form SiO₂-coated polymertemplates. Templates were formed having SiO₂ layer thicknesses of 10 nmand 15 nm as measured along the top of the gratings (with sidewall SiO₂thicknesses correspondingly reduced to 2.5 nm and 5 nm, respectively).These SiO₂-coated polymer templates were subjected to imprint testing asdescribed in Example 3, and likewise each template exhibited goodpattern transfer without showing any local or global separation failure,or feature shearing, breakage or distortion.

Example 8: Template Bending

The 15 nm SiO₂ coated polymer template of Example 8 was subjected torepeated bending to replicate use conditions associated withroll-to-roll imprinting. Specifically, the template (80 mm by 80 mm) wasbent into a curve having an approximately 5 mm radius then allowed toreturn to its normal configuration. This process was repeated 20 timesand the template was inspected by SEM. No surface cracking or otherdamage was observed.

Example 9: UV Transmission

SiO₂ templates prepared according to Example 7 above were tested for UVand visible light transmission. These templates had SiO₂ layerthicknesses of 10 nm, 16 nm, and 23 nm, respectively. Also tested forcomparison were AuPd and AgPd templates formed according to Example 2above, as well as bare polycarbonate film. Air was used as reference.The 10 nm, 18 nm and 23 nm SiO₂ coating showed essentially the same UVtransmission (75-76%) as bare PC film at A=365 nm. The AuPd and AgPdcoated templates, by contrast, had transmission levels of 41° A and 44%respectively, about a 45% loss relative to the SiO₂ coated templates.

Example 10: Template Formation (Atmospheric Pressure Plasma Jet Process,APPJ)

SiO₂-like material (SiO_(x)) coated polymer templates using atmosphericpressure plasma jet (APPJ) were formed as follows. The initial patternedfilm was formed as described in Example 2. These pre-patternedpolycarbonate film were then subject to APPJ deposition system (SurfxTechnologies, Redondo Beach, Calif.) to coat SiO_(x) material in variousthicknesses (5 nm, 10 nm, 23 nm, 33 nm and 43 nm).Tetramethylcyclotetrasiloxane (TMCTS) precursor mixed with heliumdilution gas and oxygen reacting gas was used. APPJ deposition headfixed on x-y stage was moved over the pre-patterned film surface with 10mm gap at ambient environment to form the SiOx-coated polymer templates.

Example 11: Patterning Performance

SiO_(x)-coated polymer templates prepared according to Example 10 weresubjected to imprint testing as described in Examples 3 and 7. Eachtemplate exhibited good pattern transfer without showing any local orglobal separation failure, or feature shearing, breakage or distortion.

Further modifications and alternative embodiments of various aspectswill be apparent to those skilled in the art in view of thisdescription. Accordingly, this description is to be construed asillustrative only. It is to be understood that the forms shown anddescribed herein are to be taken as examples of embodiments. Elementsand materials may be substituted for those illustrated and describedherein, parts and processes may be reversed, and certain features may beutilized independently, all as would be apparent to one skilled in theart after having the benefit of this description. Changes may be made inthe elements described herein without departing from the spirit andscope as described in the following claims.

1-10. (canceled)
 11. A method of forming an imprint lithography template, the method comprising: forming a polymer layer on a surface of a base layer; forming a pattern in the polymer layer to create a patterned polymer layer; selecting a metal from a group consisting of Gold Palladium (AuPd), Silver Palladium (AgPd), Gold (Au), Silver (Ag), Platinum (Pt) and alloys thereof; determining a desired layer thickness as a function of both the selected metal and an attribute of the pattern; and depositing the selected metal on the patterned polymer layer to form a metal layer of the determined desired layer thickness.
 12. The method of claim 11, wherein the desired layer thickness is between 2 and 50 nanometers.
 13. The method of claim 11, wherein forming the pattern in the polymer layer to define the patterned polymer layer comprises contacting the polymer layer with an additional imprint lithography template.
 14. The method of claim 13, wherein forming the pattern in the polymer layer to define the patterned polymer layer comprises, after contacting the polymer layer with the additional imprint lithography template, solidifying the polymer layer to define the patterned polymer layer.
 15. The method of claim 11, wherein the base layer comprises silicon, glass, or a flexible film.
 16. The method of claim 11, wherein depositing the selected metal includes depositing the selected metal on the patterned polymer layer by sputtering.
 17. The method of claim 11, wherein depositing the selected metal includes depositing the selected metal on the patterned polymer layer by evaporation.
 18. The method of claim 11, wherein depositing the selected metal includes depositing the selected metal on the patterned polymer layer by atomic layer deposition (ALD).
 19. A method of forming an imprint lithography template, comprising: forming a polymer layer on a surface of a base layer; forming a pattern in the polymer layer to create a patterned polymer layer; selecting a type of metal of a metal layer to be formed on the patterned polymer layer; determining a desired layer thickness of the metal layer as a function of both i) the selected type of metal of the metal layer and ii) an attribute of the pattern of the patterned polymer layer; and depositing the selected metal on the patterned polymer layer to form the metal layer of the determined desired layer thickness by one of sputtering, evaporation, or atomic layer deposition.
 20. The method of claim 19, wherein the metal is selected from a group consisting of Gold (Au), Gold Palladium (AuPd), and alloys thereof.
 21. The method of claim 19, wherein the metal is selected from a group consisting of Silver (Ag), Platinum (Pt), Silver Palladium (AgPd), and alloys thereof.
 22. The method of claim 19, wherein the desired layer thickness is between 2 and 50 nanometers.
 23. The method of claim 19, wherein forming the pattern in the polymer layer to define the patterned polymer layer comprises contacting the polymer layer with an additional imprint lithography template.
 24. The method of claim 23, wherein forming the pattern in the polymer layer to define the patterned polymer layer comprises, after contacting the polymer layer with the additional imprint lithography template, solidifying the polymer layer to define the patterned polymer layer.
 25. The method of claim 19, wherein the base layer comprises silicon, glass, or a flexible film. 